The present invention relates to a joint for a playen, and particularly to one which can be collapsed and spread easily without possibility of getting damaged by incorrect operation due to only a barb release from a pin, and user may use big force to collapse the other barb to result in damaging support rods of the playen.
Referring to FIGS. 8 and 9, a conventional joint for a playen that was patented in U.S. Pat. No. 5,730,542, has a main base 5, two wing bases 6, a press block 7 and two elongated plate hooks 8.
The main base 5 has two lengthwise side portions 51, 52, and an upper arch-shaped bridge 53 connecting upper ends of the lengthwise side portions 51, 52. The main base 5 has a center hole 531 with an annular curved-down 532 (FIG. 9) on the upper arch-shaped bridge 53. The side portions 51, 52 each has two position holes 511, 521; the position holes 511 are each aligned with a corresponding one of the position holes 521.
The wing bases 6 are formed of V-shaped plates, and each connected to a support rod of the playen, and are pivoted to the main base 5 from the position holes 511, 521 by means of pins 63.
The depress block 7 has two vertical slots 71 parallel to each other, two side recesses 72, a through hole 721 on the side recesses 72, and an upper recesses 73. The elongate plate hooks 8 are each fixed to one of the side recesses 72 by means of a pin 84 connected to the hole 721. The plate hooks 8 each has two guide curves 81 on outer ends and two barbs 82. The depress block 7 is disposed under the arch-shaped bridge 53 of the main base 5 with a spring 54 disposed in between; the spring 54 is connected to the curved-down edge 532 and the upper recess 73 to bias the press block 7 downwardly.
Two pins 56 are provided, each passed through a respective one of the vertical slots 71 of the press block 7 and the lengthwise side portions 51, 52 such that the press block 7 can be moved up and down, confined by the vertical slots 71.
The wing bases 6 each further has a pin 62, 64 fixed to a lower portion to engage the barbs 82 of the plate hooks 8 to support the playen in a spread position.
To fold the playen, first the support rods are pivoted inwardly of the main base 5 to disengage the pins 62, 64 from the barbs 82. Then, the depress block 7 is moved up and the support rods are pivoted outwardly of the main base 5; the pins 62, 64 of the wing bases 6 will contact the guide curves 81 of the plate hooks 8, permitting the support rods to be pivoted further up for the joint to be folded.
However, the above joint for a playen is found to have a disadvantage that one of the pins 62 or 64 which engage the barbs 82 is likely to engage the barbs 82 when the other one has disengaged, and the corresponding support rod has been moved to the folded position due to a somewhat tight connection between the wing bases 6 and the main base 5. In this case, the user might exert big force to try to move the support rod which is still fixed by the plate hook 8 without first disengaging the pin 62 or 64 from the barbs 82. Consequently, the associated parts and the support rod itself might get damaged.
Therefore, it is a main object of the present invention to provide a joint for a playen, which can be folded very easily and without possibility of damaging the parts when a shaped hole is provided.
The joint of a playen of the present invention includes a main base, two wing bases, a press block and two elongated plate hooks.
The main base has two lengthwise side portions and an upper arch-shaped bridge connecting tops of the side portions. The side portions each has a shaped hole shaped like a water chestnut.
The wing bases are pivoted to the side portions of the main base and each connected to a support rod of a playen. The wing bases each has a locating pin fitted thereto.
The press block is movably connected to the main base, and has a long vertical guide hole. A guide pin is passed through the guide hole and the shaped hole of the main base to confine a movement of the press block.
The elongated plate hooks are fixed to the press block, and each has two end barbs.
The support rods are supported at a spread position by means of the locating pins engaging the barbs. To move to the support rods to a folded position, the support rods are slightly pivoted inwardly of the main base, and the press block is pushed up; thus, the support rods can be pivoted upwards to the folded position. The guide pin can move in the shaped holes sideways to permit the press block to move sideways, helping the barbs to separate from the locating pins of the wing bases easily in can one of the locating pins fails to disengage from the barbs in the above said operation.